We know three main methods of generating terahertz (THz) waves. The current trend in technology is the use of opto-electronic THz wave generation methods based on photoconductive antennas.
Terahertz spectroscopy is divided into two domains: the time domain and the frequency domain. The time domain uses a femto second laser with THz bandwidth to generate, while the time domain uses two DFB lasers and an optical multiplier. The latter is presented in Figure 1, and Figure 2 shows the commercial TeraScan system from Toptica Photonics.
Data processing in terahertz spectroscopy is based on identification and quantization methods. Identification methods are based on measuring the spectral properties of the measured sample - absorption and reflectivity. Quantization methods, however, are mostly based on chemometric methods, most commonly PCA and PLS analysis.
Terahertz technology for spectroscopy and image capture is still in its infancy. Due to its high cost and complexity, it is only available in laboratory form for laboratory experimentation. With the development of new, cheaper and less complex methods of generating THz waves, the technology will also become more accessible for use in industry.
Figure 1: Structure of the spectrometer in the time domain according to the spectrometer of the manufacturer Toptica Photonics
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